1. Field
This disclosure relates generally to integrated circuits, and more specifically, to integrated circuits using standard cells.
2. Related Art
Standard cells are basic building blocks in the design of integrated circuits. An integrated circuit typically includes a variety of different standard cells. A standard cell is a group of transistors and interconnect structures which provide a particular function, such as a Boolean logic function (e.g. AND, OR, XOR, XNOR, NAND, NOR, inverters, etc.) or a storage function (e.g. flip flop, latch, etc.). Standard cells may also provide more complex functions, such as an adder, a multiplexor (MUX), etc. The functionality of a particular cell is fully customizable. Standard cells also typically have a fixed height and variable width which allows for easy placement in rows within a circuit design.
As integrated circuits continue to increase in complexity, a greater number of standard cells is used. Subtle changes to standard cells can play an important role in the overall integrated circuit performance and yield. Therefore, the area constraints and performance characteristics for a standard cell become increasingly important. For example, any increase in area of a standard cell results in an increased area of the integrated circuit, which is undesirable. Also, variability in performance and leakage of a standard cell can significantly contribute to yield loss. Therefore, a need exists for standard cells having an increased robustness without increasing circuit area.